Jane Horrocks as Ros Pritchard

What happens when a perky supermarket manager from West Yorkshire finds herself at the head of a political movement that sweeps her into office as Britain's new prime minister? For starters, how about moving England's capital, demoting the queen and doing something about global warming? Masterpiece Theatre charts the frantic life of a truly unusual politician in "The Amazing Mrs. Pritchard," a new five-part series beginning Sunday, Oct. 21 at 9/8 p.m. CT on KET1 and Thursday, Oct. 25 at 9/8 p.m. CT on KET2.

Jane Horrocks (Life Is Sweet, Little Voice ) stars as Ros Pritchard, a perfect boss and attentive mother hen to her workers at Greengages Superstore in rural Eatanswill, until one day a fistfight erupts outside between two local candidates for Parliament -- men, of course. "I could do better than you lot!" she exclaims after breaking up the scuffle to the applause of bystanders and reporters. Egged on by the media, who see her as a breath of fresh air during a lackluster campaign, Ros impulsively files as a candidate.

In no time, she is leading a feminist revolution in British politics, with like-minded women all over the country following her example to run for Parliament as part of the new Purple Democratic Alliance.

The miniseries features Steven Mackintosh as Ros' overwhelmed husband, Ian, who has mysterious reasons for wanting her to stay out of politics; Jodhi May as Miranda Lennox, Ros' idealistic advisor, who has a practical Karl Rove side; and Janet McTeer as Catherine Walker, a high-ranking member of the Conservative Party, who defects to the Purple Alliance at a crucial moment and is rewarded with the post of chancellor and deputy prime minister.

"The Amazing Mrs. Pritchard " is produced by Kudos Film and Television; Masterpiece Theater is presented by WGBH/Boston.